Over the course of the spontaneous decomposition of Pd-bound oxadiazoline N-heterocyclic carbenes, the reaction system includes four types of species (free and coordinated isocyanates, free and coordinated imines) and can be assumed the possibility of the formation of various types of four-membered heterocycles via [2 + 2]-cycloaddition. However, has not been detected the formation of any such structures. This theoretical study focuses on the reasons why in Pd-activation conditions isocyanates and imines do not react with each other.